fifocache: fix potential double-free

pkg/fileservice/fifocache/data_cache.go

@@ -80,6 +80,7 @@ func (d *DataCache) deletePath(ctx context.Context, shardIndex int, path string)
 	for key, item := range shard.values {
 		if key.Path == path {
 			delete(shard.values, key)
+			// key deleted, call postEvict
 			if d.fifo.postEvict != nil {
 				d.fifo.postEvict(ctx, item.key, item.value, item.size)
 			}

pkg/fileservice/fifocache/fifo.go

@@ -200,6 +200,7 @@ func (c *Cache[K, V]) Delete(ctx context.Context, key K) {
 		return
 	}
 	delete(shard.values, key)
+	// key deleted, call postEvict
 	if c.postEvict != nil {
 		c.postEvict(ctx, item.key, item.value, item.size)
 	}
@@ -290,9 +291,12 @@ func (c *Cache[K, V]) deleteItem(ctx context.Context, item *_CacheItem[K, V]) {
 	shard := &c.shards[c.keyShardFunc(item.key)%numShards]
 	shard.Lock()
 	defer shard.Unlock()
-	delete(shard.values, item.key)
-	if c.postEvict != nil {
-		c.postEvict(ctx, item.key, item.value, item.size)
+	if _, ok := shard.values[item.key]; ok {
+		delete(shard.values, item.key)
+		// key deleted, call postEvict
+		if c.postEvict != nil {
+			c.postEvict(ctx, item.key, item.value, item.size)
+		}
 	}
 }
 

pkg/fileservice/fifocache/fifo_test.go

@@ -115,3 +115,23 @@ func TestCacheEvict3(t *testing.T) {
 	assert.Equal(t, 2048, nSet)
 	assert.Equal(t, 2048, nGet)
 }
+
+func TestDoubleFree(t *testing.T) {
+	evicts := make(map[int]int)
+	cache := New(
+		fscache.ConstCapacity(1),
+		ShardInt,
+		nil, nil,
+		func(ctx context.Context, key int, value int, size int64) {
+			evicts[key]++
+		},
+	)
+	// set
+	cache.Set(t.Context(), 1, 1, 1)
+	// delete, item still in queue
+	cache.Delete(t.Context(), 1)
+	// set to evict 1
+	cache.Set(t.Context(), 2, 2, 1)
+	// check
+	assert.Equal(t, 1, evicts[1])
+}